CVE-2007-2461 in PIX
Summary
by MITRE
The DHCP relay agent in Cisco Adaptive Security Appliance (ASA) and PIX 7.2 allows remote attackers to cause a denial of service (dropped packets) via a DHCPREQUEST or DHCPINFORM message that causes multiple DHCPACK messages to be sent from DHCP servers to the agent, which consumes the memory allocated for a local buffer. NOTE: this issue only occurs when multiple DHCP servers are used.
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Analysis
by VulDB Data Team • 01/25/2025
The vulnerability identified as CVE-2007-2461 affects the DHCP relay agent functionality within Cisco Adaptive Security Appliance (ASA) and PIX firewall devices running software version 7.2. This issue represents a classic buffer overflow condition that manifests specifically in environments utilizing multiple DHCP servers, creating a denial of service scenario that impacts network availability and operational continuity. The flaw occurs when the DHCP relay agent processes certain DHCPREQUEST or DHCPINFORM messages that trigger an excessive number of DHCPACK responses from multiple DHCP servers, ultimately leading to memory exhaustion within the device's local buffer allocation.
The technical mechanism behind this vulnerability involves the improper handling of DHCP message processing within the ASA and PIX firewall's DHCP relay agent component. When multiple DHCP servers are present in the network environment, the relay agent receives DHCPACK messages from each server in response to the malicious DHCPREQUEST or DHCPINFORM traffic. The buffer allocated for handling these responses becomes insufficient to accommodate the volume of messages generated, causing memory allocation issues that result in dropped packets and network service disruption. This behavior aligns with CWE-129, which addresses improper handling of buffer boundaries, and specifically demonstrates how inadequate input validation can lead to resource exhaustion attacks. The vulnerability is particularly concerning because it only manifests when multiple DHCP servers are configured, making it more prevalent in complex enterprise network environments where redundancy and failover mechanisms are implemented.
From an operational impact perspective, this vulnerability creates significant disruption to network services by causing intermittent or complete denial of service conditions within the affected firewall infrastructure. Network administrators may observe dropped packets, failed DHCP negotiations, and potential network segmentation issues that can affect end-user connectivity and business operations. The attack vector requires remote access to the network, making it accessible to adversaries who can exploit the vulnerability without physical presence or privileged network access. The issue is particularly dangerous in environments where the ASA or PIX firewall serves as a critical network gateway, as the denial of service can cascade through the entire network infrastructure, affecting multiple subnets and user segments. This vulnerability directly maps to ATT&CK technique T1498, which covers network denial of service attacks, and represents a specific implementation weakness in network infrastructure security devices.
Mitigation strategies for CVE-2007-2461 should prioritize immediate patching of affected devices with Cisco's security updates, which address the buffer handling issue in the DHCP relay agent. Network administrators should also implement monitoring solutions that can detect unusual DHCP traffic patterns and excessive DHCPACK message generation, allowing for early identification of potential exploitation attempts. Configuration changes may include limiting the number of DHCP servers in the relay environment or implementing additional network segmentation to isolate DHCP traffic. Organizations should also consider implementing rate limiting or traffic filtering rules that can prevent the specific DHCPREQUEST and DHCPINFORM message patterns that trigger the vulnerability. The remediation approach must account for the fact that this vulnerability only occurs in multi-server DHCP environments, so network architects should carefully evaluate their DHCP infrastructure design to minimize exposure. Additionally, regular security assessments and vulnerability scanning should be conducted to identify similar buffer handling issues in other network security appliances and ensure comprehensive protection against related attack vectors.